Field of the Invention
The present invention relates to an optical apparatus, such as an interchangeable lens and an image capturing apparatus, which includes a lens barrel provided with a main aperture stop and a sub aperture stop.
Description of the Related Art
Aperture stops provided to a lens barrel change a stop aperture formed by multiple stop blades by moving the multiple stop blades in an open and close direction to control a light amount. The lens barrel includes ones provided with a main aperture stop that mainly controls the light amount and a sub aperture stop to correct a diameter of a fully-opened stop aperture (hereinafter referred to as “a fully-opened stop aperture diameter”) set by the main aperture stop depending on a focal length and an object distance or to prevent a significant change in a marginal light amount caused by a zoom operation.
Japanese Patent Laid-Open No. 2001-83565 discloses a lens barrel provided with a sub aperture stop that corrects the fully-opened stop aperture diameter in response to a focusing operation. On the other hand, Japanese Patent Laid-Open No. 9-222628 discloses a lens barrel that changes, in response to a zoom operation, a distance in an optical axis direction between a main aperture stop and a sub aperture stop disposed on an image side further than the main aperture stop to perform flare cutting by the sub aperture stop so as to prevent a significant change in a marginal light amount caused by the zoom operation.
Typical aperture stops each drive the stop blades in the open and close direction by using an actuator. The lens barrel disclosed in Japanese Patent Laid-Open No. 2001-83565 drives the stop blades in the main aperture stop by the actuator and, however, drives the stop blades in the sub aperture stop without using the actuator. In this disclosed lens barrel, a rotating member that drives the stop blades in the sub aperture stop has a cam portion extending in the optical axis direction, and the cam portion has a cam groove portion with which a cam follower provided to a movable lens engages. When the movable lens is moved in the optical axis direction, the rotating member is rotated about the optical axis by a lift of the cam groove portion, which drives the stop blades.
Lens barrels whose lenses have special optical characteristics such as an ultra-wide-angle lens require, in addition to the main aperture stop, at least two sub aperture stops, namely, one sub aperture stop correcting the fully-opened stop aperture diameter and another sub aperture stop performing the flare cutting so as to prevent the significant change in the marginal light amount. These lens barrels each require a configuration that enables separately adjusting diameters of stop apertures of the two sub aperture stops while suppressing an increase in cost and in number of parts. Moreover, in these lens barrels, the sub aperture stops may have mutually different fully-opened stop aperture diameters.
However, prior art documents including Japanese Patent Laid-Open Nos. 2001-83565 and 9-222628 fail to disclose such a lens barrel provided not only with the main aperture stop, but also with two or more sub aperture stops.